Particle and Azure IoT Hub: forward events for storage and analysis

In a previous post about Partice published events, you have seen how to publish custom events to the Particle Cloud. Other devices or applications can subscribe to these events and act upon them. What if you want to do more and connect these events to custom applications? In that case, Particle has a couple of integrations that might help:

In this post, I will take a look at Azure IoT Hub integration which, at the moment of writing, is still in beta. Note that this integration works with events you publish from your device with Particle.publish and not with Particle Variables or Functions. Remember that in the post about events, we published a lights on and lights out event. For simplicity, we will build upon those events here.

An IoT Hub that you create from the portal; to get started, use the free tier which allows you to publish 8000 events per day (give or take; depends on message size as well); in the portal, use the + button

An IoT Hub has a name and works with shared access policies and access keys to be able to control the IoT Hub and send messages. To get to the policies, just click Shared Access Policies.

Although considered bad practice, I will use the iothubowner policy which has all required rights. Click iothubowner to view the access keys and note the primary access key. You will need that key in a moment.

In Particle Console, click the Integrations icon and click new integration. In the configuration screen, you will see:

It’s pretty self explanatory once you have your IoT Hub created in Azure. Just fill in the required information and note that the event name is the name of the event you have given in the call to Particle.publish. My events are called lights on and lights out and I will use lights as Event Name. This will catch both events!

To test this, the photoresistor was given enough light to fire the events. This is the result when you click on the integration after it was created:

When you click on one of the log entries, you will see more details:

You see the event payload that was sent to IoT Hub plus details about the call to IoT Hub using HTTP POST.

In IoT Hub, you will see a couple of things as well. First of all, the events:

In the list of devices, you will find a device with the id of the Particle Photon:

Note: Azure IoT Hub requires devices to authenticate but this is taken care of automatically by Particle Cloud

What you do now with these messages is up to you. You can use the new endpoints and routes feature of IoT Hub to forward events to Event Hubs or Service Bus. Or you could connect Stream Analytics to IoT Hub and save your events to Azure Storage, Data Lake, SQL, Document DB or stream the data to a real-time Power BI dashboard.

Note that although an Azure Subscription is free, not all services have free tiers. For instance, IoT Hub has a free tier but Stream Analytics does not. And although IoT Hub’s free tier is great to get started, it can only process a limited amount of events. It’s up to you to control the rate of events sent from your devices. For home use or small PoCs you should not run into issues though!